If there is a one-minute span that best sums up what’s gone on with the Thunder in the first five days of their Western Conference title defense, it began with 2:30 to play in the fourth quarter at home on Sunday against the Hawks, who were shorthanded without star forwardJosh Smith. Atlanta was up, 95-91, and the ball went to center Zaza Pachulia in the high post, guarded by Kendrick Perkins. Guard Lou Williams, who had been chewing up the Oklahoma City defense in the quarter with 10 points, was coming off an Al Horford baseline screen on the low left block. Horford’s man, Serge Ibaka, was eager to keep the ball out of Williams hands, and lost track of Horford, who rolled toward the rim. Pachulia found him in the paint, and Horford had an easy dunk.

On the next trip down the floor, after an offensive rebound by the Hawks, Williams had the ball on the top of the 3-point arc on the left side. Pachulia set a high screen for Williams, with OKC’s Perkins and Russell Westbrook double-teaming the ball. Pachulia rolled to the paint, Williams passed to him and when Kevin Durant left DeShawn Stevenson to provide help defense, Pachulia found Stevenson for a wide-open 3 in the right corner. Stevenson nailed the shot, and the resulting nine-point lead with 1:28 to play was too much for the Thunder to overcome.

The Thunder are trying, for sure. But, in the wake of the stunning James Harden trade that went down just before the season began, they’re under an extraordinary amount of pressure. They’re too passive at times, too aggressive at others and have not found balance. The Thunder are trying too hard on offense, forcing too many bad shots and ill-advised passes—they committed 20 turnovers against the Hawks, after committing 30 in their first two games. And cracks in the defense that showed throughout last season and into the Finals are still showing up.

“I think we just all want it so bad right now and we all have to realize, it’s not April or May or June yet,” Kevin Martin said after the Hawks loss. “It’s Game 3. So we have to come into practice, watch some film and have a better showing on Tuesday.”

Most of what has ailed the Thunder will take care of itself. In the next two weeks, Oklahoma City will play six of eight games against teams that did not make the playoffs last year, and that will help set things right in the win-loss column. But even if they’re winning, they still need to play much better overall, particularly on the defensive end. Oklahoma City misses Harden’s ability to run the offense, especially pick-and-roll plays, which allows Westbrook to play off the ball down the stretch of games—that was obvious as the Thunder struggled to just six points in the final four minutes on Sunday. Martin has more than adequately replaced Harden’s scoring ability, though, averaging 20.7 points and shooting 70.3 percent on 3-pointers through three games.

What has the attention of coach Scott Brooks and his star forward, Durant, is the defense. The Thunder big men—Ibaka and Perkins—allowed far too much paint scoring (42 points), and Horford only provided further evidence that Perkins can be rendered useless by mobile big men. When he was matched up on Perkins, Horford was able to step out and face up against him, either setting himself up for a jumper or lining up to drive past Perkins. As more teams go small in the frontcourt (see: Miami Heat, 2012 Finals) the problem of employing a big, slow-footed center like Perkins becomes more obvious the Thunder.

Also troubling is the internal sniping reported by beat writer John Rhode of the Oklahoman—after Sefolosha and Westbrook had words for each other going into the locker room at halftime of Friday’s win over Portland, Rhode reported that Sefolosha and Westbrook had to be separated at the end of the first quarter on Sunday. Last year, remember, Westbrook was frustrated with Sefolosha during a game in Memphis (telling him to “Shoot the ball!” with a special seven-letter adjective between “the” and “ball”), leading to a much-publicized bench confrontation between Durant and Westbrook.

That wasn’t as much of a storm as the media made it out to be, it turned out, and the Thunder went on to win the conference and reach the Finals. The early shuffling of the team this year could turn out to be as inconsequential. But the Harden trade has ramped up the pressure on the players still with the Thunder, and the core of the team has been together too long to have the kinds of defensive lapses they showed on Sunday against an inferior group on their home floor.

“It shouldn’t be going back and forth,” Durant said. “We’re a defensive team and we can’t have that many breakdowns in a game, we just can’t. That goes down the line, it is for everybody, not just one person. Everybody on the team. So it’s something to learn from.”

There are still 79 games in which to learn for the Thunder. But without Harden, there is much yet to learn.